Compelling evidence suggests that mitochondrial dysfunction contributes to the pathogenesis of heart failure, including defects in the substrate oxidation, and the electron transport chain (ETC) and oxidative phosphorylation (OXPHOS). However, whether such changes occur early in the development of heart failure, and are potentially involved in the pathologic events that lead to cardiac dysfunction is unknown. To address this question, we conducted transcriptomic/metabolomics profiling in hearts of mice with two progressive stages of pressure overload-induced cardiac hypetrophy: i) cardiac hypertrophy with preserved ventricular function achieved via transverse aortic constriction for 4 weeks (TAC) and ii) decompensated cardiac hypertrophy or heart failure (HF) caused by combining 4 wk TAC with a small apical myocardial infarction. Transcriptomic analyses revealed, as shown previously, downregulated expression of genes involved in mitochondrial fatty acid oxidation in both TAC and HF hearts compared to sham-operated control hearts. Surprisingly, however, there were very few changes in expression of genes involved in other mitochondrial energy transduction pathways, ETC, or OXPHOS. Metabolomic analyses demonstrated significant alterations in pathway metabolite levels in HF (but not in TAC), including elevations in acylcarnitines, a subset of amino acids, and the lactate/pyruvate ratio. In contrast, the majority of organic acids were lower than controls. This metabolite profile suggests bottlenecks in the carbon substrate input to the TCA cycle. This transcriptomic/metabolomic profile was markedly different from that of mice PGC-1a/b deficiency in which a global downregulation of genes involved in mitochondrial ETC and OXPHOS was noted. In addition, the transcriptomic/metabolomic signatures of HF differed markedly from that of the exercise-trained mouse heart. We conclude that in contrast to current dogma, alterations in mitochondrial metabolism that occur early in the development of heart failure reflect largely post-transcriptional mechanisms resulting in impedance to substrate flux into the TCA cycle, reflected by alterations in the metabolome.
Energy metabolic reprogramming in the hypertrophied and early stage failing heart: a multisystems approach.
Sex, Age, Specimen part
View SamplesMouse MycT58A/DNp53 (MP) medulloblastoma cells were treated with DMSO or HDAC inhibitor (HDACi) panobinostat for 6 or 12 hours in vitro.
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Treatment
View SamplesThe tumor microenvironment plays a critical role in cancer progression, but the precise mechanisms by which stromal cells influence the tumor epithelium are poorly understood. The signaling adapter p62 has been implicated as a positive regulator of epithelial tumorigenesis; however, its role in the stroma is unknown. We show here that p62 levels are reduced in the stroma of several tumors. Also, orthotopic and organotypic studies demonstrate that the loss of p62 in the tumor microenvironment or stromal fibroblasts resulted in increased tumorigenesis of epithelial prostate cancer cells. The mechanism involves the regulation of cellular redox through an mTORC1/c-Myc pathway of stromal glucose and amino acid metabolism. Inhibition of the pathway by p62 deficiency results in increased stromal IL-6 production, which is required for tumor promotion in the epithelial compartment. Thus, p62 is an anti-inflammatory tumor suppressor that acts through modulation of metabolism in the tumor stroma.
Metabolic reprogramming of stromal fibroblasts through p62-mTORC1 signaling promotes inflammation and tumorigenesis.
Specimen part
View SamplesNatural populations of the fruit fly, Drosophila melanogaster, segregate genetic variation that leads to cardiac disease phenotypes. Drosophila is well-known as a model for studying the mechanisms by which human disease genes cause pathology, including heart disease, but it is less well appreciated that they may also model the genetic architecture of disease, since flies presumably also have diseases that have a genetic basis. It is reasoned that most of these aberrant inbred line effects would be due to capture of rare variants of large effect as homozygotes, allowing the variants to be mapped rapidly using contemporary genomic approaches.
Complex genetic architecture of cardiac disease in a wild type inbred strain of Drosophila melanogaster.
Age
View SamplesThe following abstract from the submitted manuscript describes the major findings of this work.
A role for peroxisome proliferator-activated receptor γ coactivator-1 in the control of mitochondrial dynamics during postnatal cardiac growth.
Specimen part
View SamplesGene expression from bone-marrow drived macrophages of WT and SREBP-1a deficient mice
Linking lipid metabolism to the innate immune response in macrophages through sterol regulatory element binding protein-1a.
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View SamplesThis SuperSeries is composed of the SubSeries listed below.
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Specimen part
View SamplesCharacterized by striking metastatic propensity and chemoresistance, melanoma is among the most lethal cutaneous malignancies. The transcription factor ATF2 was shown to elicit oncogenic activities in melanoma, and its inhibition attenuates melanoma development. Here, a mouse model engineered to express a transcriptionally inactive form of Atf2 (Atf2?8,9) was found to be sufficient to induce nevi formation and, when crossed with BrafV600E animals, to promote melanoma development. The cross of Atf2?8,9 with BrafV600E;Pten-/- mice augmented pigmentation, tumorigenicity, and metastasis. Similar to mouse Atf2?8,9, the human ATF2 splice variant 5 enhanced growth and migration capacity of cultured melanoma and immortalized melanocytes. Induced Melan-A, CXCL9, S100A8, CCR7 expression, seen in Atf2?8,9-driven tumors associate with their enhanced pigmentation, immune infiltration and propensity to metastasize. Notably, elevated ATF2SV5 expression in melanoma specimens coincided with poor prognosis. The gain-of-function activity elicited by the truncated ATF2 form offers unexpected insight into mechanisms underlying melanoma development and progression.
No associated publication
Specimen part
View SamplesAim of study was to determine what was causing the liver tumors in the SART1+/- mice
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Sex, Age, Specimen part, Disease
View SamplesThe development of insulin resistance is strongly associated with accumulation of intracellular lipid in tissues outside of adipose including skeletal muscle, liver and heart. In obese humans, intramyocellular lipid (IMCL) is negatively correlated with whole body insulin sensitivity. The skeletal myocyte imports fatty acids (FA) into the cell from circulating free fatty acids or lipoprotein particles such as VLDL, to support energy production. Once transported into the cell, FAs are oxidized for ATP production, used to build membranes, or stored as triglyceride. However, in the long term, increased delivery of fatty acids can exceed mitochondrial oxidative capacity and set the stage for a vicious cycle of cellular lipotoxicity. We have recently identified a novel small molecule inhibitor of lipid accumulation in skeletal mycytes termed SBI-477. Microarray transcriptomics was performed in primary human skeletal myotubes following oleate loading and treatment with SBI-477. This was also compared to A922500, a diacylglycerol transferase 1 (DGAT1) inhibitor. SBI-477 treatment reversed many of the transcriptomic effects of oleate loading in these cells but also produced a transcriptomic profile distinct from the DGAT1 inhibitor.
MondoA coordinately regulates skeletal myocyte lipid homeostasis and insulin signaling.
Treatment
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